Coated fabric and composition for coating the same



Patented Feb. 29, 1944 COATED FBRlO 2,343,180 AND comosrrlon Fon DATING THE SAME Otto Helm, Philadelphia, Pa., .assignor to Rehn- Hitner Developing Corporation, Inc., Philadelphia, Pa., a corporation of New York No Drawing.

The present invention relates to a new and useful fabric composition and structure and more particularly to .a fabric'composition and structure in which the base fabric material is comprised of finely attenuated fibers of glass which are twisted into strands and the strands woven into a fabric structure, the attenuated fibers and their associated coherent structure being known as glass cloth or Fiberglas, a trade-mark name owned by the Owens-Corning Flberglas Corporation of Toledo, Ohio.

The invention also relates to a new and useful liquid coating composition for application by brush or other means of spreading or by submersion impregnation to the Fiberglas cloth, the glass cloth and its dried coating constituting the improved fabric composition.

The improvedfabric composition comprising the present invention is primarily adapted for use as a waterproof and fireproof covering for airplane wings and other parts although the principles of the invention are applicable to other uses and the fabric may be utilized in the waterproofing and fireprooflng of semi-rigid and rigid dirigibles, seagoing ships, as a lining for acid proof chambers in submarines, in the construction of parachutes, tarpaulin covers, tents, temwill not transmitmoisture from the outside to porary or permanent buildings, and for a variety of other uses both military and industrial.

Many of the present day coating compositions when applied to fabric compositions will prevent spreading of flame inasmuch as they are compounded on the principle that they will evolve an extinguishing gas when heated. Such coating compositions and the resultant fabric composition or structure resulting therefrom are effective to a certain extent to accomplish the purpose for which they are intended but they are subject to the very material criticism that in so evolving gas their internal structure is broken down and many of the inherent original properties thereof such as their waterproofing or insulatingcharacteristics are destroyed permanently.

Glass cloth or Fiberglas is generally considered to be fireproof in itself due to its inability to readily burnwhen encountering a flame of relatively short duration and of low intensity. Such glass material however is actually far from being destructible when an intense flame or a prolonged one'is applied thereto. Ordinarily Fiberglas cloth is comprised of twisted strands of F1- berglas which are woven together in a uniform manner to produce a fabric structure. Each strand-is comprised of 102 very fine strands of pure glass which are attenuated mechanically Application February 2.19 42, SerialNo. 429,348

'1 Claims. ('01. 106-245) from a series of small openings provided in the lower end of a platinum bushing which serves as a melting pot for the raw batch. Because of the fact that the diameterof each fiber of the glass material is in the neighborhood of only five microns, the individual fibers are susceptible to melting, even under the influence of direct flames.

This Fiberglas material is also consideredto be waterproof but its waterproofing features are confined solely to the waterproof nature of the individual strands of glass which, of course, are

extremely dense and which cannot therefore become impregnated with moisture and swell or shrink. The glass cloth which is formed from the Fiberglas fibers however is not waterproof in the sense that it will repel moisture or that it the inside thereof or that water will not cling to it. a

For the reasons outlined above Fiberglas cloth has not been altogether satisfactory for use as a waterproof and a fireproof covering for air-' plane wings and parts. Indeed its water proofing features are decidedly lacking inasmuch as water will cling to and collect in the fabric interstices under the influence of capillary attraction and if a cold atmosphere sufllcient to induce freezing is encountered, the consequent expansion of the water during its conversion into ice will distort the'tiny fragile glass strands and rupture the same.

Numerous other limitations are attendant up- I on the use of ordinary Fiberglas cloth in this manner and these will become readily apparent from the inferences derived in describing the present invention.

Myimproved product, including both the coat ing composition and thefabric produced by its application to Fiberglas cloth, is designed to overcome many of the limitations that are attendant upon the use of untreated Fiberglas cloth as a covering for airplane wings and parts, or for other uses. The coating composition is adapted to be applied to the cloth by a brushing operation or by impregnation wherein the cloth is dipped in the liquid composition and it includes certain chemical fireproofing ingredients, certain stiffening ingredients, certain moisture repelling and waterproofing ingredients, certain strength-- ening ingredients, certain preservative ingredients and certain ingredients whiclf render the composition adhesive or cohesive so that the glass cloth to which it is applied and the product which thus obtain; is admirably well suited for aircraft and marine purposes as set forth above.

Numerous other advantages of my improved coating composition and of the product obtained by its application to glass cloth will become readily apparent as the nature of the invention is better understood.-

I have found that the most advantageous method of applying the liquid composition to the glass cloth is by either a brushing or dipping operation, although spraying may be resorted to if desired. The application by any of these methods may be conducted in either dry or humid atmosphere and either at room temperatures or at freezing or extremely hot temperatures. If the application is made out of doors inclement weather is no deterrent to satisfactory application and subsequent drying. Drying under ordinary conditions ordinarily takes place in a few minutes.

Immediately prior to compllete drying and while the coating is still moist I spread thereon by means of a brush or the like or by spraying or dipping a 4% solution of sodium silicate and allow the treated coating to resume drying. The sodium silicate lends body to the dried coating and assists in closing the interstices of the cloth. Because of the fact that the silicate does not penetrate the coating it will not attack the silica of the individual glass fibers.

The texture of the base. sheet of Fiberglas may vary according to use but ordinarily I prefer to use fine mesh material comprised of dual twisted strands, each strand being comprised of 120 fibers of glass, each fiber being approximately 5 microns in diameter.

The composition is essentially a liquid one 'and the following is one example of a compound formed according to my invention and found by actual test to be very successful:

Per cent by Ingredient weight Amyl acetate Ricinus 011.-.... Sodium nitrate In the above composition each of the ingredients contributes an important characteristic to the mixture. The amyl acetate (commonly known as lacquer or banana oil) afiords fiexibility to the dried coating so that it may be flexed without cracking or otherwise becoming ruptured and at the same time it renders the liquid coating adhesive so that it will, after penetration of the interstices between the glass fibers m strands, not become dislodged therefrom. it absorbs any moisture that may be present on the glass cloth at the time the coating is applied and thus prevents any pockets of moisture within the coating or beneath the same and it also contributes to the fire-proofing features of the composition. The ricinus oil (which is commonly known as castor oil) lends smoothness to the finished product and is water and ice repellant and assists in shedding moisture or ice that ordinarily is likely to collect upon airplane wings or other parts. The sodium nitrate serves to combine or put in solution certain of the other ingredients while at the same time the nitrate crystals themselves are readily soluble in the other ingredients. The nitrate also lends a degree of elasticity to the coating and prevents brittleness. The parafllne serves the dual function of rendering the whole extremely tough and durable and adds tensile strength thereto while at the same time it serves to neutralize the corrosive action of the silicate ingredient which otherwise would attack the relatively minute fibers of glass and partially or completely dissolve the same. The nitroglycerine after combination with the silicate assists the waterglass in rendering the coating inflammable.

The boric acid serves to neutralize the odor of the amyl acetate and it also, like the amyl acetate itself, lends a degree of flexibility to the product and prevents cracking or peeling thereof. The thinner, which may be of any suitable commercial variety, serves. its natural function of rendering the liquid coating readily applicable by a brushing process or submergence of the glass cloth in the liquid while the ether also performs its natural function of rendering the coating a quick drying one. The ether and thinner in combination served to cause the liquid solution to penetrate the interstices of the fabric and to reach all hidden surfaces thereof and to throw more or less evenly thereon. These ingredients also constitute a wetting agent whereby such flow of the liquid is facilitated.

The composition is quick drying and noncrystalline and in no way attacks, softens, or weakens the glass fibers or strands to which it is applied.

The proportions of the various ingredients as given above may be varied to a considerable extent and an alternative example of a suitable coating composition is given below Ingredient ggjg g Amyl acetate Ricinus oil.

- ingredients may be added as adulterants to secure other properties such as Coloring properties and the like without departing from the spirit of the invention. In general the specific ingredients employed in each case is more or less dependent upon the specific purpose for which the glass fabric coated material is intended.

The exact proportion of no one ingredient of my improved composition is critical. The amyl acetate may be contained in the solution in proportions ranging from 12% to 30%. glass may exist in proportions of from 4% to 7%; ricinic acid in proportions of from 8 to 15; sodium nitrate 8 to 15, etc.

Fiberglas cloth treated according to my invention undergoes a material increase in tensile strength. Furthermore the coating. when dried adds but little to the overall weight of the original glass cloth. Three and one-half ounces of the liquid coating material will treat one square yard of the material when a brushing or dipping operation is employed. This amount of coating material will increase the tensile strength of th The water fabric to the extent where a one-inch wide strip of treated fabric will support a weight of from 170 to 180 pounds as compared to an original 80 to'90 pounds. Its cross strand tensile strength on a similar one inch strip of material is over ten pounds whereas its tear or shear strength is over three pounds.

The coating when dry is colorless and odorless and does not increase the weight of the original fabric unduly. It is nonhygroscopic, non poisonous, non-corrosive, and resists removal during normal usage. It adheres firmly to the glass fabric; it will not attract colors that may be present in the o'riginal Fiberglas even though these col- 9138 are superficial coating colors rather than inherent in the glass batch; it will not only protect the glass from the effects of flame but it is additionally non-glowing. It is insect proof and will not mildew or support a fungus growth or otherwise deteriorate when used as a covering in marine use whether exposed to fresh or salt water. When applied to such use it protects the surface which it covers from erosion and incrustation. It can be applied not only to the raw Fiberglas product but it may be applied in situ to finished articles.

What is claimed is:

1. As an article of manufacture, a base sheet of woven glass fabric having a coating thereon applied as a mixture comprised of at least in part of amyl acetate, ricinus oil, sodium nitrate, para ffin. nitroglycerine, and boric acid.

2. A liquid coating solution consisting of amyl acetate, ricinus oil, sodium nitrate, paramn, nitroglycerine, boric acid, and a thinner.

3. As an article of manufacture, a base sheet of woven glass fabric having a coating thereon applied as a mixture comprised at least in part of 25% amyl acetate, 10% ricinus oil, 12% sodium nitrate, 8% paraflin, 8% nitroglycerine, and 17% boric acid.

4. As an article of manufacture, a base sheet of woven glass fabric having a coating thereon applied as a mixture comprised of at least in part of 20% amyl acetate, 10% ricinus oil, 12% sodium nitrate, 5% paraflln, 8% nitroglycerine, and 15% boric acid.

5. As an article of manufacture, a base sheet of woven glass fabric impregnated with a coating applied as a mixture comprised of from 1230% amyl acetate, 815% ricinus oil, 10%-15% sodium nitrate, 3 to 8% 'paraflin, 510% nitroglycerine, and Iii-20% boric acid.

6. As an article of manufacture, a base sheet of woven glass fabric having a coating thereon ap- I plied as a mixture comprised of at least in part of amyl acetate, ricinus oil, sodium nitrate, paraffin, nitroglycerine, and boric acid, to which there has been applied a solution of sodium silicate.

7. As an article of manufacture, a base sheet of woven glass fabric having a coating thereon comprised of approximately 4% sodium silicate and having an outer coating thereon applied as a mixture comprised of amyl acetate, ricinus oil, sodium nitrate, paraflln, nitroglycerine, and boric acid. 

